The present invention is directed to elongate intracorporeal devices, and particularly intraluminal devices for stent deployment, percutaneous transluminal coronary angioplasty (PTCA), and the similar procedures that are facilitated by an inflatable tubular member. The invention is also directed to elongated intracorporeal devices, such as guidewires, used for guiding intraluminal devices for stent deployment, PTCA and similar procedures.
PTCA is a widely used procedure for the treatment of coronary heart disease. In this procedure, a balloon dilatation catheter is advanced into the patient""s coronary artery over a guidewire and the balloon on the catheter is inflated within the stenotic region of the patient""s artery to open up the arterial passageway and increase the blood flow through the artery.
To facilitate the advancement of the dilatation catheter into the patient""s coronary artery, a guiding catheter having a preshaped distal tip is first percutaneously introduced into the cardiovascular system of a patient by the Seldinger technique through the brachial or femoral arteries. The catheter is advanced therein until the preshaped distal tip of the guiding catheter is disposed within the aorta adjacent the ostium of the desired coronary artery.
The guiding catheter is torqued from its proximal end outside the patient to guide the shaped distal end into a desired coronary ostium. Once the distal end of the guiding catheter is properly seated in the coronary ostium, a balloon catheter may then be advanced through the guiding catheter into the patient""s coronary artery over a guidewire until the balloon on the catheter is disposed within the stenotic region of the patient""s artery.
Once properly positioned across the stenosis, the balloon is inflated one or more times to a predetermined size with radiopaque liquid at relatively high pressures (e.g., generally 4-12 atmospheres) to dilate the stenosed region of a diseased artery. After the inflations, the balloon is finally deflated so that the dilatation catheter can be removed from the dilated stenosis to resume blood flow.
Similarly, balloon catheters may be used to deploy endoprosthetic devices such as stents which are generally cylindrical shaped intravascular devices. These devices are expanded within a damaged artery to hold the artery open. The device can be used to prevent restenosis and to maintain the patency of blood vessel immediately after intravascular treatments. Typically, a compressed or otherwise small diameter stent is disposed about an expandable member such as a balloon on the distal end of a catheter, and the catheter and stent thereon are advanced through the patient""s vascular system in the same manner as described above for dilatation catheters. Inflation of the balloon expands the stent within the blood vessel. Subsequent deflation of the balloon allows the catheter to be withdrawn, leaving the expanded stent within the blood vessel.
The proximal shaft section of a balloon catheter or other percutaneous device will often include a tubular member made from high strength materials such as stainless steel, chromium-cobalt alloys such as MP35N, superelastic NiTi alloys, high strength composite materials or the like. The high strength tubular member gives the proximal shaft section the column strength and pushability required for the device while maintaining an inner lumen of sufficient bore for inflation or deflation of an expandable member disposed at the distal section of the balloon catheter. The high strength tubular members can be susceptible to kinking and breaking while being manipulated through tortuous body channels during use. Also, it can be difficult to bond various polymeric materials to many of these high strength tubular members which complicates the manufacturing process and increases the price of the catheter.
To solve these shortcomings, the high strength tubular member is often jacketed with high strength extruded polymer tubing to provide heat bondable polymeric material on the outside surface of the high strength tubular member in order to more easily secure the member to other components of the catheter. In addition, the high strength extruded polymer jacket material provides added safety to the catheter in the event that the high strength tubular member kinks or breaks inside a patient during a surgical procedure. If the high strength tubular member kinks or breaks while inside a patient during a surgical procedure, the high strength extruded polymer jacket can provide a resilient sheath which is not subject to kinking or breaking that enables the physician to withdraw the catheter from the patient without the need for surgical intervention.
While it is desirable to have a high strength extruded polymer jacket over the high strength tubular member, the jackets usually have to be applied as relatively thick tubular sections in order to prevent them from bulging out from the high strength tubular member when high pressure fluids are injected into the lumen within the proximal shaft section. Such a jacket having a relatively thick wall section can add considerably to the cross sectional area of the proximal shaft of the catheter which reduces the amount of cross sectional area available for the inflation/deflation lumen which can complicate the surgical procedure. What has been needed is a catheter having a proximal shaft section with a high strength tubular member that is jacketed with a high strength extruded polymer jacket with a relatively thin wall section that is not subject to bulging out from the high strength tubular member under high inflation pressures.
Similarly, it is often desirable to provide the core member of a guidewire with a polymer jacket in order to maintain the outer diameter of the guidewire in portions where the core has been distally tapered to provide greater flexibility. A polymer jacket may also provide a desired outer surface texture for a guidewire, including added lubricity to facilitate advancement of the guidewire through a patient""s vasculature during a procedure, irrespective of whether the jacket maintains a constant outer diameter.
Thus, what has also been needed is a reliable process for securing a polymer jacket to the outside surface of a metallic portion of an intraluminal devices such as guidewires and catheters.
The present invention satisfies these and other needs.
The invention is directed to an intracorporeal device which has a polymer jacket securely bonded to a high strength member of the intracorporeal device by a polymeric adhesive.
The intracorporeal devices embodying features of the invention have elongated high strength members with polymeric jackets which are bonded to the surfaces by polymeric adhesives.
In one embodiment, a balloon catheter has an elongate shaft with a proximal section formed at least in part of a high strength tubular member and a polymer jacket disposed about the high strength tubular member. The polymer jacket comprises an outer layer of high strength polymer and an inner layer of an polymeric adhesive polymer disposed between and bonding the outer layer to the high strength tubular member. In another embodiment, a guidewire has an elongate core with a distal section formed at least in part of a high strength member and a flexible polymeric body disposed about the distal section of the elongate core. The flexible polymeric body disposed about at least a portion of the elongate core comprises an outer layer of polymeric material and an inner layer of polymeric adhesive disposed between and bonding the outer layer to the elongate core.
Preferably, the adhesive polymer layer includes an adhesive polymer selected from the group consisting of ethylene acrylic acid copolymer and functionally modified polyolefins. The outer polymeric layer preferably comprises a polymer selected from the group consisting of polyurethane, nylon 12 and a polyether block amide such as PEBAX (which is sold by Elf Atochem).
The invention also comprises methods of securing a polymer jacket to a elongate high strength intracorporeal member, including coextruding a polymer jacket having an polymeric outer layer and a polymeric adhesive inner layer and necking the polymer jacket over the high strength shaft at a temperature above the melting temperature of the adhesive polymer inner layer and below the melting temperature of the polymeric outer layer.
The multilayered jacket secured to the high strength tubular or other elongated member allows for a significant reduction in the thickness of the outer polymer layer, e.g. thickness reductions of up to about 0.002 inch (0.05 mm) or more. These and other advantages of the invention will become more apparent from the following detailed description and the accompanying exemplary drawings.